These sense-impressions we project as it were outwards and term the real world outside ourselves.

But the things-in-themselves which the sense-impressions symbolize, the 'reality,' as the metaphysicians wish to call it, at the other end of the nerve, remains unknown and is unknowable.

Reality of the external world lies for science and for us in combinations of form and color and touch--sense-impressions as widely divergent from the thing 'at the other end of the nerve' as the sound of the telephone from the subscriber at the other end of the wire.

We are cribbed and confined in this world of sense-impressions like the exchange clerk in his world of sounds, and not a step beyond can we get.

As his world is conditioned and limited by his particular network of wires, so ours is conditioned by our nervous system, by our organs of sense.